 /*******************************************************************************
  * Copyright (c) 2004, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal;

 import java.util.ArrayList ;
 import java.util.Iterator ;
 import java.util.List ;

 import org.eclipse.swt.SWT;
 import org.eclipse.swt.events.SelectionAdapter;
 import org.eclipse.swt.events.SelectionEvent;
 import org.eclipse.swt.widgets.Menu;
 import org.eclipse.swt.widgets.MenuItem;

 /**
  * Represents a group of radio buttons in a menu. Each menu item
  * is mapped onto a particular value. The RadioMenu reports its state
  * using the attached Model object. That is, Model.getState() will
  * return the value of the currently selected radio button and Model.setState(value)
  * will select the radio button associated with the given value.
  */
 public class RadioMenu implements IChangeListener {

     private Model data;

     private Menu parent;

     private List items = new ArrayList ();

     SelectionAdapter selectionAdapter = new SelectionAdapter() {
         public void widgetSelected(SelectionEvent e) {
             Object newState = e.widget.getData();

             data.setState(newState, RadioMenu.this);
         }
     };

     /**
      * Creates a set of radio menu items on the given menu.
      *
      * @param parent menu that will contain the menu items
      * @param newData the model that will store the value of the currently selected item
      */
     public RadioMenu(Menu parent, Model newData) {
         this.parent = parent;
         this.data = newData;

         newData.addChangeListener(this);
     }

     /**
      * Returns true iff the given values are considered equal.
      *
      * @param value1
      * @param value2
      * @return
      */
     private static boolean isEqual(Object value1, Object value2) {
         if (value1 == null) {
             return value2 == null;
         } else if (value2 == null) {
             return false;
         }

         return value1.equals(value2);
     }

     /**
      * Creates a new menu item with the given text and value. When
      * the item is selected, the state of the model will change to
      * match the given value.
      *
      * @param text
      * @param value
      */
     public void addMenuItem(String text, Object value) {
         MenuItem newItem = new MenuItem(parent, SWT.RADIO);

         newItem.setSelection(isEqual(data.getState(), value));
         newItem.setText(text);
         newItem.setData(value);
         items.add(newItem);

         newItem.addSelectionListener(selectionAdapter);
     }

     /**
      * Disposes all menu items
      */
     public void dispose() {
         Iterator iter = items.iterator();
         while (iter.hasNext()) {
             MenuItem next = (MenuItem) iter.next();

             if (!next.isDisposed()) {
                 next.removeSelectionListener(selectionAdapter);
                 next.dispose();
             }
         }

         items.clear();
     }

     /**
      * Refreshes the selected menu items to match the current state of the model.
      */
     private void refreshSelection() {
         Iterator iter = items.iterator();
         while (iter.hasNext()) {
             MenuItem next = (MenuItem) iter.next();

             if (!next.isDisposed()) {
                 next.setSelection(isEqual(data.getState(), next.getData()));
             }
         }
     }

     /* (non-Javadoc)
      * @see org.eclipse.ui.internal.controls.IView#changed()
      */
     public void update(boolean changed) {
         refreshSelection();
     }

 }

